Home > CBCT-based dental implant planning and surgical guides solve surgical and prosthetic challenges

CBCT-based dental implant planning and surgical guides solve surgical and prosthetic challenges

Objectives:

The aim of this case report is to identify the accuracy outcome of cone-beam computed tomography (CBCT) based surgical guides for implant placement in partially edentulous patient with an anterior mandible bone defect due to a bullet received in war. The aim is to demonstrate guided implant placement and the application of fixed, implant-supported prosthetic restorations with a fully digital workflow.

Material and methods:

I used cone beam computed tomography FONA XPan 3D (CBCT). CBCT DICOM files exported can be merged with scan appliance DICOM files to create 3D renders that support virtual planning of prosthetic restorations and “crown down” surgical planning. We should use the scan appliance for this case to be planned from both a prosthetic and surgical perspective.

3D printed surgical template printed by (3D Atom printer), and milling by CAD/CAM machine (Roland DWX50) of a fiberglass framework (Bioloren Trilor Disc) veneered with visioline composite material (Bredent company).

Conclusions:

The present procedure for fully digital planning of implants and implant-supported restorations has shown to be reliable.

Case presentation:

A 60-year-old male in good health with multiple missing teeth in the lower arch (Fig. 1). The patient reported he had a gun shot during the war in 1976. The patient was first seen in May 2016 in my dental centre in Alexandria, Egypt, with a stated desire for using dental implants to restore the missing teeth.

Fig.1 Extraoral and intraoral view, demonstrating absence of almost mandibular teeth and the bone defect related to the area of gunshot surgery.

Treatment plan:

After a discussion of the alternatives, benefits, and complications of treatment options, the patient stated that he wished to receive implant restorations. It was agreed that a custom surgical guide would be created using CBCT and digital scanning technology, for the ultimate purpose of facilitating guided placement of the dental implants. Fig.1 Extraoral and intraoral view, demonstrating absence of almost mandibular teeth and the bone defect related to the area of gunshot surgery.

Scan procedure:

A CBCT scan was taken (with FONA XPan 3D) of the patient wearing the dual scan appliance and the dual scan appliance alone with the radiographic markers. The resultant DICOM data files were exported to the planning software, then merged to produce a 3D render. (Fig.2,3)

Fig.2 Virtual render of Radiographic Guide

Fig.3 Demonstrates merging of the virtual render of the radiographic guide with 3D render of the patient.

Virtual planning:

Using the principles of “crown down” planning. Using the implant placement planning features of the Blue Sky Plan 3 software, an optimised position of the 5 implant fixtures was developed. I planned to extract tooth #43 due to infection, keeping in mind the restoration will provide total implant support. I placed a fixation pin on the left side to maintain stability of the guide during drilling. This case demonstrates the value of virtual planning, as there were several anatomical and dental issues requiring close attention to fixture placement detail. The bone defect shape and hard tissue anatomy exhibit limited freedom of placement, given the position of the inferior alveolar canal, mental foramen, and lingual mylohyoid concavity. (Fig.4,5,6)

Fig.4 Demonstrates the virtual planning of the case.

Fig.5 Demonstrates the virtual surgical guide with implant in position.

Fig.6 The printed surgical guide with guide sleeves and the guided kit compatible with the planning software.

Surgical procedure:

After a review of the patient’s health history, including basic vital signs, such as blood pressure and pulse, informed consent was received. The patient was given two 1.8 ml carpules of Lidocaine Hydrochloride 2% with 1: 100,000 Epinephrine. Upon profound local anaesthesia, with the surgical guide in place, tissue punch was used to remove a precise cylinder of tissue to access the mandibular ridge of bone at the planned implant surgical site. OXY guided drills were used to perform the surgical procedure. The drill series consisted of an initial “flare” drill (Guided Start Drill) a 2mm depth drill (Guided 2.0 Twist Drill) and sequential full-depth drills (Guided Tapered Drills) to match the implant fixture shape.

These drills were used to precisely create the osteotomy in all dimensions of space, including depth. Both implant sites were drilled to the precise depth and shape for planned implant placement.

A 12mm long Oxy implant (Biomec. SRL Italy) 4mm in diameter was placed at the site of the teeth #31 and #41. A 12mm long implant 4.5mm in diameter was placed at the site of the teeth #44 and #46. While the implant placed at tooth site #36 was 8mm long, 5mm in diameter. Using a manual torque wrench, the implants were rotated into place such that the shoulder of the implant fixture holder mated with the surgical guide at a torque value of 35 Ncm. (Fig.7)

Fig.7 demonstrate panoramic x-ray show the real implant placement after surgery .

Implant restoration:

After 10 days, the patient returned for restoration of the implants. The screw-retained fiberglass framework (Biloren ,Trilor fiberglass disc) was milled and veneered with Visioline lab. composite (Bredent company) and were made with a titanium insert (Oxy titanium base (Biomec. SRL Italy)) to allow a titanium- to-titanium interface between the crown and implant connection. The restoration was designed by Exocad software abutment module.

The patient was seen for try-in and delivery. The healing abutments were removed so that the restorations could be seated and then tightened into place using the supplied titanium retention screws and a standard abutment driver. A manual torque wrench was used to tighten the titanium retention screws of implants to a value of 35 Ncm. The occlusal access holes were filled with Teflon plumber’s tape and the access holes sealed with TPH® 3 universal composite resin (Dentsply Caulk; Milford, Del.) . The occlusion was checked in various functional positions as well as maximum intercuspation, with an objective to minimize lateral occlusal forces as may be transmitted to the implant fixture. The occlusal composite was checked in occlusal function.

The patient was seen for a post crown insertion visit after two weeks to reevaluate the crowns, and they were deemed to have an excellent fit and occlusal relationship (Fig.8).

FIG .8 Demonstrate the final implant restoration.

Conclusion:

Recent imaging and software development now enables the merging of CBCT DICOM files with STL files or DICOM files of scan appliance. Virtualwax-up and planning may be done to create surgical guides, with simultaneous consideration of hard tissue and optimal restoration location, providing clinicians a higher level of confidence when placing implants. Final implant restoration may be done with digital scanning systems such as 3d progress intraoral scanner using dedicated inclusive scanning abutments, which are available for a number of the most popular implant systems. Remarkable advances in implant crown manufacture allow laboratories to create screw-retained crowns in a 100 % digital environment without conventional models.

The promises of the digital future of dentistry can help dentists and their patients to realize the dream of “make it simple”.

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About Doctor

Bassem Mohamed EL-Ashrafy

Owner of Bassem Dental Center , Alexandria, Egypt

BDS, MSc university of Alexandria
Fellowship of ICOI
Private experience and owner of dental lab, CAD CAM and 3D printing. Tel:00201064347513
55 El-Rasafa street, Alexandria , Egypt
Email:bassemalashrafy@gmail.com

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